TBS games are my choice also....
Alpha Centauri is my all time favorite computer game and while my new box also will not run it, I keep a computer nearby that will. It is also the only game I have ever played well. I (once) won a game on transcend level as my favorite faction, The University. I usually play at a lower difficulty since it takes too damn long and is too damn hard on transcend.
Other tbs games worth trying are Civ III and Galactic Civilizations. The only RTS game I could ever play half ass was AOE about 5 years ago. I am just too old for RTS anymore.
BTW, I have read all four of the Ender saga and Enders Shadow is queued up on my nightstand for when I finish the Night's Dawn trilogy.
Xenocide and Children of the Mind are worth reading.